Self-aligned imprint lithography (SAIL) is one method of forming electronic components and circuit elements. For example, SAIL can be used to form thin-film transistors on a flexible substrate.
In such cases, the flexible substrate is coated using a roll-to-roll process with a number of stacked thin-film layers that will form the transistors. An etchable masking structure is formed over the thin-film stack. A pattern corresponding to the transistor components needed is impressed into the masking structure, creating variations in the height of the masking structure. The result is then etched. Compressed portions of the masking structure will be etched away more quickly resulting in a deeper further etching of the underlying thin-film stack. In this way, the pattern impressed into the masking structure is transferred to the stacked thin-film layers. Consequently, alignment is maintained whether or not process-induced distortions exist.
Some of the layers in the thin-film stack provide electrical connections between transistor components and are, therefore, conductive. However, because the patterning is imprinted into the stack using a single three-dimensional masking structure, it can be an issue to electrically connect different levels and portions of the conductive layers together from the surface of the substrate to form the transistor of other circuit element being made.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.